Lithography is utilized in the fabrication of semiconductor devices to transfer a pattern onto a wafer. Based on various integrated circuit (IC) layouts, patterns of a mask are reduced by a factor of 2:1 or 4:1 in order to transfer the pattern to a surface of the wafer. The mask, also called a reticle, is made of a substrate with one or more opaque materials deposited on one side to block penetration of a lithographic radiation. A clear region is configured to reflect or transmit the lithographic radiation. As dimensions decrease and density in IC chips increases, resolution enhancement techniques, such as extreme ultraviolet (EUV) exposure, phase-shift mask (PSM), optical proximity correction (OPC), off-axis illumination (OAI) and double dipole lithography (DDL), are developed to improve depth of focus (DOF) and to achieve a more precise pattern transfer onto the wafer.